How about doing both the clean up for this session and the set up
work for the following period at the end of each period? Overall,
this probably saves 30 or 40 percent of the time spent in setting up
and cleaning up each day.
Each end-of-class task is posted (or listed). Each table has
individuals for each task as well as a checker. When one student
completes a task, the checker assigns the person as an assistant to
another student with work remaining. More students are busy and
fewer are sitting and waiting to leave. The next class gets on task
as soon as they arrive - especially if class beginnings are
structured and predictable.
This essay discusses beginning and ending class with rituals.
http://www.goshen.edu/art/ed/ritual.html
It has a link to additional activities to start a class session.
Marvin Bartel